Research in this application is directed to fundamental problems in the function of cell membranes. A major objective is to obtain information on the processes by which cells sense the osmolarity (chemical potential of water) in the medium in which they live, and react to variations in osmolarity by appropriate adaptive responses. The experimental attack is focused on osmoregulation of the biosynthesis of membrane-derived oligosaccharides in E. coli, and on certain periplasmic oligosaccharides of Rhizobium and Agrobacterium which may play a role in these organisms similar to that of MDO in E. coli. The specific experimental objects include: (1) A study of the biosynthesis of MDO in E. coli; (2) The regulation of the biosynthesis of MDO; (3) A search for mutants pleiotropically altered in their capacity to sense or to react to changes in osmolarity of the medium; and (4) An examination of osmoregulation of the production of surface carbohydrates by species of Rhizobium and Agrobacterium.